harfbuzz/src/hb-ot-var-fvar-table.hh

211 lines
6.6 KiB
C++

/*
* Copyright © 2017 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_OT_VAR_FVAR_TABLE_HH
#define HB_OT_VAR_FVAR_TABLE_HH
#include "hb-open-type-private.hh"
/*
* fvar -- Font Variations
* https://docs.microsoft.com/en-us/typography/opentype/spec/fvar
*/
#define HB_OT_TAG_fvar HB_TAG('f','v','a','r')
namespace OT {
struct InstanceRecord
{
inline bool sanitize (hb_sanitize_context_t *c, unsigned int axis_count) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
c->check_array (coordinates, coordinates[0].static_size, axis_count));
}
protected:
NameID subfamilyNameID;/* The name ID for entries in the 'name' table
* that provide subfamily names for this instance. */
HBUINT16 reserved; /* Reserved for future use — set to 0. */
Fixed coordinates[VAR];/* The coordinates array for this instance. */
//NameID postScriptNameIDX;/*Optional. The name ID for entries in the 'name'
// * table that provide PostScript names for this
// * instance. */
public:
DEFINE_SIZE_ARRAY (4, coordinates);
};
struct AxisRecord
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this));
}
public:
Tag axisTag; /* Tag identifying the design variation for the axis. */
Fixed minValue; /* The minimum coordinate value for the axis. */
Fixed defaultValue; /* The default coordinate value for the axis. */
Fixed maxValue; /* The maximum coordinate value for the axis. */
HBUINT16 reserved; /* Reserved for future use — set to 0. */
NameID axisNameID; /* The name ID for entries in the 'name' table that
* provide a display name for this axis. */
public:
DEFINE_SIZE_STATIC (20);
};
struct fvar
{
static const hb_tag_t tableTag = HB_OT_TAG_fvar;
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (version.sanitize (c) &&
likely (version.major == 1) &&
c->check_struct (this) &&
instanceSize >= axisCount * 4 + 4 &&
axisSize <= 1024 && /* Arbitrary, just to simplify overflow checks. */
instanceSize <= 1024 && /* Arbitrary, just to simplify overflow checks. */
c->check_range (this, things) &&
c->check_range (&StructAtOffset<char> (this, things),
axisCount * axisSize + instanceCount * instanceSize));
}
inline unsigned int get_axis_count (void) const
{ return axisCount; }
inline bool get_axis (unsigned int index, hb_ot_var_axis_t *info) const
{
if (unlikely (index >= axisCount))
return false;
if (info)
{
const AxisRecord &axis = get_axes ()[index];
info->tag = axis.axisTag;
info->name_id = axis.axisNameID;
info->default_value = axis.defaultValue / 65536.;
/* Ensure order, to simplify client math. */
info->min_value = MIN<float> (info->default_value, axis.minValue / 65536.);
info->max_value = MAX<float> (info->default_value, axis.maxValue / 65536.);
}
return true;
}
inline unsigned int get_axis_infos (unsigned int start_offset,
unsigned int *axes_count /* IN/OUT */,
hb_ot_var_axis_t *axes_array /* OUT */) const
{
if (axes_count)
{
unsigned int count = axisCount;
start_offset = MIN (start_offset, count);
count -= start_offset;
axes_array += start_offset;
count = MIN (count, *axes_count);
*axes_count = count;
for (unsigned int i = 0; i < count; i++)
get_axis (start_offset + i, axes_array + i);
}
return axisCount;
}
inline bool find_axis (hb_tag_t tag, unsigned int *index, hb_ot_var_axis_t *info) const
{
const AxisRecord *axes = get_axes ();
unsigned int count = get_axis_count ();
for (unsigned int i = 0; i < count; i++)
if (axes[i].axisTag == tag)
{
if (index)
*index = i;
return get_axis (i, info);
}
if (index)
*index = HB_OT_VAR_NO_AXIS_INDEX;
return false;
}
inline int normalize_axis_value (unsigned int axis_index, float v) const
{
hb_ot_var_axis_t axis;
if (!get_axis (axis_index, &axis))
return 0;
v = MAX (MIN (v, axis.max_value), axis.min_value); /* Clamp. */
if (v == axis.default_value)
return 0;
else if (v < axis.default_value)
v = (v - axis.default_value) / (axis.default_value - axis.min_value);
else
v = (v - axis.default_value) / (axis.max_value - axis.default_value);
return (int) (v * 16384. + (v >= 0. ? .5 : -.5));
}
protected:
inline const AxisRecord * get_axes (void) const
{ return &StructAtOffset<AxisRecord> (this, things); }
inline const InstanceRecord * get_instances (void) const
{ return &StructAtOffset<InstanceRecord> (get_axes () + axisCount, 0); }
protected:
FixedVersion<>version; /* Version of the fvar table
* initially set to 0x00010000u */
Offset16 things; /* Offset in bytes from the beginning of the table
* to the start of the AxisRecord array. */
HBUINT16 reserved; /* This field is permanently reserved. Set to 2. */
HBUINT16 axisCount; /* The number of variation axes in the font (the
* number of records in the axes array). */
HBUINT16 axisSize; /* The size in bytes of each VariationAxisRecord —
* set to 20 (0x0014) for this version. */
HBUINT16 instanceCount; /* The number of named instances defined in the font
* (the number of records in the instances array). */
HBUINT16 instanceSize; /* The size in bytes of each InstanceRecord — set
* to either axisCount * sizeof(Fixed) + 4, or to
* axisCount * sizeof(Fixed) + 6. */
public:
DEFINE_SIZE_STATIC (16);
};
} /* namespace OT */
#endif /* HB_OT_VAR_FVAR_TABLE_HH */